To clarify the difference between the bolus-tracking technique and a fixed scan delay protocol in the achievement of the optimal pancreatic phase of the pancreas with MDCT.

526 patients underwent pancreatic and portal venous phase imaging of the pancreas using 16-channel MDCT. All the examinations were randomized into either scanning using a bolus-tracking technique with a scan delay of 20s after the aorta was enhanced > 100 HU (groups 1 and 2) or scanning with a scan delay of 38 s from the beginning of the injection (groups 3 and 4). A contrast material of 300 mgI/mL (groups 1 and 3) or 370 mgI/mL (groups 2 and 4) at an injection speed of 3 mL/sec was injected at 2 mL/kg body weight. The pancreatic CT attenuation values were compared.

The scan delay times of the pancreatic phase in groups 1 and 2 were 38±3.8s and 37.4±3.4s, respectively. At the pancreatic phase, the pancreatic attenuation values of groups 1 and 2 were slightly higher than those of groups 3 and 4 (115.5±15.4 vs 111.7±15.1HU; p=0.093, 128.3±17.1 vs 119±17.1HU; p=0.003). There was no significant difference between groups at the portal venous phase.

The use of a bolus-tracking technique in the optimal pancreatic phase of pancreatic CT does not significantly improve the pancreatic enhancement but does at higher iodine concentrations.